This invention relates to a clamping band for affixing an electromagnetic shielding sleeve to an electrical cable connector or the like.
Electrical cables comprising a plurality of electrical conductors often are encased in a woven metal braid for the purpose of shielding the conductors from electromagnetic and radio frequency interference. The individual conductors are terminated at an electrical connector, and it is required that a mechanically secure and electrical low resistance connection be made between the woven shielding braid and the connector. This has been accomplished in the past by various arrangements, and various problems have been encountered. One problem is the bulk and awkwardness of the tool utilized for securing the clamp, thereby limiting the locations at which the tool can be used. By way of example, many electrical cables are utilized in aircraft with very limited space and very limited access, and therefore it is highly desirable to have a clamping band which can be installed without requiring operation of a bulky tool.
Another desirable feature is the ability to remove and replace the clamping band during maintenance operations and/or when conductors in a cable are being changed or redirected. This requires a type of clamping band which can be removed in the field without damage to the cable, and which can be installed in the field, often when only limited resources in the form of tools and power are available.
By way of example, some types of tools require some form of power such as electric, air or hydraulic, and it is an object of the present invention to provide a clamping band which can be affixed with a hand operated tool. Another type of conventional clamping band comprises a unity ring which is positioned around the braid and connector and electromagnetically formed to compress the band onto the sleeve. While this provides a very satisfactory mechanical and electrical connection, it requires insertion of the cable into the electromagnetic forming equipment which ordinarily is only possible in a factory situation.
Other problems with conventional band termination of shield braid reside the fact that some require a slight reverse motion in order to lock the band in the buckle, with a resultant loosening in the clamping and poor electrical contact. Another band design provides for locking the buckle with a direct forming blow, as by a hammer, resulting in damage to the connecting device or the inner tube. Bands of these types have primarily been used for fastening rubber hoses onto tubes or fittings or for holding packages together, which permits the clamping band to be compressed and slightly relaxed for tightening and which will withstand punch or hammer type impact. In contrast, the electromagnetic type of shield braid must be held tightly in place without use of any elastomeric components which could flow and loosen during use. Since the electrical connectors typically are thin walled aluminum alloy, impact type connections are not satisfactory.
Accordingly, it is an object of the present invention to provide a new and improved clamping band for clamping braid shield sleeves onto electrical connectors to provide electromagnetic and radio frequency interference shielding. A further object is to provide such a band which can be positioned around the assembly and which does not require sliding axially over the assembly, and a band which can be tightened by pulling and locked in place by folding over, without requiring any impact fastening or elastomeric fastening.
It is an object of the invention to provide such a clamping band that is tightened by pulling which can be accomplished by simple hand operated tools in locations of limited access. A particular object is to provide such a clamping band which is flexible throughout its length, including the buckle section, so as to make a substantially 360.degree. continuous contact between the band and the shielding sleeve.
A further object is to provide a new and improved buckle configuration with the buckle wings firmly joined together and with the inner of the loops formed by the wings contiguous with the strap and with the outer of the loops of constant width.
Other objects, advantages, features and results will more fully appear in the course of the following description.